In aircraft, retaining devices are used for retaining a wide variety of components; for example, air-conditioning systems, in particular heat exchangers and/or compressors of an air-conditioning system, are fastened to a fuselage structure of an aircraft by means of retaining devices.
DE 100 35 301 C2 discloses a retaining device for an air-conditioning system. This retaining device comprises a suspension frame which extends from the fuselage structure. A plurality of suspension rods extend from the suspension frame and are connected, at their ends remote from the suspension frame, to an air-conditioning system.
The suspension rods can be connected to the air-conditioning system via a ball head construction at the suspension points. The ball head construction allows a deflection of the ball heads in a particular range, in order to compensate a fuselage structure movement. In the case of deflections of the fuselage structure in axial and/or vertical directions owing to a hard landing, for example, structural components made of CFRP can have a greater movability than structural components made of metal. Large movements of structural components can lead to an increase in the reaction forces on system components.
To absorb increased reaction forces, the material thickness of components of the retaining device can be increased. Increasing the material thickness results in an increase in rigidity, and this in turn leads to higher reaction forces owing to a lower flexibility of the components. Alternatively, the number of suspension rods can be reduced, and this increases the movability of the aircraft components. However, a reduction in the number of suspension rods is limited owing to the acceleration forces and the maximum load-bearing capacity of the retaining device. Also, the construction of the retaining device should not be changed fundamentally, since official requirements with respect to safety are met by the number of rods owing to the redundancy.